NV3X Architecture Overview

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NV3X Architecture Overview - Page 1

ATI
didn?t fail to impress us with the
R300 launch. Clearly, the RADEON 9700 will be the next
leading performance graphics solution for the high end, at
least for a while. However, NVIDIA is not sitting idle,
watching ATI capture market share. The release of
DirectX 9 is approaching and the finishing touches are
being applied to NV30, NVIDIA?s successor to the GeForce4.
If you think of R300 as Germany?s Bismarck battleship,
NV3X can be likened to Britain?s HMS Hood, sent to
intercept and destroy the powerful adversary. Of
course, NVIDIA hopes the outcome of the confrontation
won?t end the same way. HMS Hood met a fiery demise
at the hand of Bismarck?s 15? guns. The following is
a brief overview of the NV3x architecture, based on what
we know at this juncture and are allowed to disclose to
you. NVIDIA's is turning its big gun toward ATi.
The battle has just begun.

That special sauce - Shaders Version 2.0

DirectX 9
requirements and beyond

Both the
R300 and NV3X architectures are similar in several ways.
The DirectX 9 standard is one of the most influential
reasons for this. To begin with, both the Pixel and
Vertex Shader specifications have been updated to version
2.0. With DirectX 8, the GeForce4 is limited to a
maximum of 128 instructions per vertex shader program.
NVIDIA?s ?CineFX? architecture increases that number to
1024 static instructions, giving developers a greater
level of flexibility for creating more complex effects.
Additionally, dynamic flow control allows loops, jumps and
branches within the shader programs, increasing the total
number of vertex instructions to a theoretical maximum of
65,536.

Pixel
processing has also been elevated in importance.
DirectX 8?s Pixel Shader 1.1 specification allows for four
textures per pixel (version 1.4 can do six). Shader
programs are limited to four texture instructions and
eight color instructions. NV3X, on the other hand,
supports shader programs 1,024 instructions long with up
to 16 textures per pixel for procedural effects that do
not require texture maps. Both ATI and NVIDIA are
citing procedural wood as an example of a pixel shader 2.0
effect. ATI?s R300 can also apply 16 textures per
pixel, but is limited to 160 instructions per pass.
This is where NVIDIA stands to gain a significant
advantage over ATI ? if developers choose to make heavy
use of long pixel shader programs, R300 will require
multiple passes to process a shader program whereas NV3X
will not.